This application relates to a fire protection method and system, particularly, for the protection of residential occupancies, although the fire protection method and system are applicable to other occupancies as well.
In the long history of fire protection technology in the United States, going back to the 1800s, it has been conventional to design and to construct fire prevention sprinkler systems that use, as a fire-extinguishing fluid, water supplied from a pipe system that is separate from the pipe system that supplies drinking water to an occupancy.
U.S. Pat. No. 4,964,471 shows one example of such a sprinkler system. The system is designed for use with ducts carrying corrosive gases, and has a multiplicity of sprinkler assemblies, each having an easily replaceable adapter with a sprinkler head having a fusible alloy fill. The sprinkler head is screwed into one end of the adapter that has an integral flange at an opposite end. The adapter is inserted into a flanged nozzle that is part of the duct. The adapter flange is bolted to the nozzle flange that has a central opening adapted for connection to a source of an extinguishing fluid.
An element of such a sprinkler is shown in U.S. Patent Application Publication No. 2002/0011527. This publication discloses a sprinkler head that includes a body having one end adapted for connection to a supply of pressurized fluid, another end that is closed by a valve element, and a thermally responsive assembly for normally holding the valve element in a closed position and for opening the valve element at a preset temperature to cause the pressurized fluid to flow out of the other end of the body. The thermally responsive assembly includes a holder and a fusible alloy that is contained within the holder and held in place by a plunger.
A further possible element of this type of a sprinkler is shown in International Publication No. WO 03/105962. This publication discloses a sealing cap for a nozzle in a sprinkler system, in which the nozzle is formed as a spray nozzle of the turbo type that is connected in series in the sprinkler system, and in which the sealing cap is fitted over the nozzle and is arranged to protect the nozzle lying inside.
As a result of requirements imposed by governmental fire codes and by insurers, commercial and other public buildings, including large, multi-residential occupancies, are normally provided with a fire protection sprinkler system when first built. With increased attention to fire safety in the single-family home, however, a need exists for a way to install such a system in single-family residences more easily and at a lower cost. If a potable-water supply of a building can also be used to supply water to the fire protection sprinkler system, it is possible to dispense with a large amount of additional piping that would otherwise be required. As a result, the expense involved in installing such a system can potentially be lowered, especially in a building having relatively little space for plumbing.
Moreover, environmental considerations may also lead to a preference for a fire protection sprinkler system that can receive water from the same interior piping supply as used for domestic-use water in a building.
With conventional fire protection sprinkler systems, however, this is not possible because the materials conventionally found suitable for use in constructing a fire protection sprinkler contain levels of lead and various other substances that preclude the use of those materials on elements exposed to potable (i.e., drinking) water. As one requirement, for example, the materials that form surfaces of fire protection sprinklers that are exposed to potable water must have a lead content of not more than 0.25% by weight. As another example, such materials must have a single product allowable concentration (“SPAC”) for lead of less than or equal to 0.5 μg per liter (0.5 part per billion), a total allowable concentration (“TAC”) for lead of less than or equal to 5 μg per liter (0.5 part per billion), and lead test statistic Q of less than 5 μg when normalized for a 1 liter first draw sample, when the test statistic Q is defined in accordance with the National Sanitation Foundation and American National Standards Institute Standard for Drinking Water System Components 61-2010a Annex F (NSF/ANSI 61-2010a Annex F).